Is it ok to have blocking operations in a resolver/mutation when using the parallel parser?

@kenny no. It will freeze your system sometimes a dummy solution is wrap your blocking ops with a thread https://github.com/souenzzo/graph-demo/blob/master/src/main/souenzzo/graph_demo/core.clj#L99

Hmm. That seems a bit sketchy.

@kenny if you use the thread pool feature, its ok

the thread pool thing will run resolvers in a dedicated thread pool, so they wont block the go block threads

https://wilkerlucio.github.io/pathom/v2/pathom/2.2.0/connect/thread-pool.html

@wilkerlucio Oh cool! So then you don't need to return a core.async thread from each resolver, right?

correct

even if you don't use the thread pool, its ok to return strait values

the thread pool just ensures you are not blocking the go threads

And the benefit over the regular parser is that the resolvers are run in parallel, right?

correct 👍

@kenny just a caveat, tune that number, nowadays I believe 200 is too much, at Nubank we are running pretty big instances with 100 and its been fine

depending on how much concurrency you are expecting it may be good to bump the Go thread pool as well (core.async default is 8, we are using 32)

The go thread pool wouldn't need to change if I'm passing a thread pool to Pathom, correct? We don't really use go blocks.